Machine for spreading and finishing plastic pavements



NOV. 1, 1938. w FRENCH 2,134,689

\ MACHINE FOR SPREADING AND FINISHING PLASTIC PAVEMENTS Filed May 8, 1935 2 Sheets-Sheet l ggy 1 ImfenIBF.

. Wk I 44? 21 Nov. 1, 1938. A. w; FRENCH MACHINE FOR SPREADING AND FINISHING PLASTIC PAVEMENTS 2 Sheets-Sheet 2 Filed May a, 1935 lrufeni Patented Nov. 1, 1938 PATENT OFFICE MACHINE FOR .S PREADING AND FINISHING PLASTIG PAVEMENTS" Alfred W. French, Chicago, Ill.

Application May 8, 1935, Serial No. 20,426

15 Claims. (01. 94-46) In the concrete or plastic pavement and construction art, it has been demonstrated that the plastic material is rendered very dense and free from gas pockets and surplus moisture by subjecting thesame tosevereagitation such asstrong vibration, as contemplated by the device of Letters Patent to Stubbs, No. 918,388.

\Ithas also been demonstrated that if plastic material, ,such as concrete, is disposed upon a pavement strip to a level appreciably higher than the level or contour of the ultimate pavement slab and is then subjected to manipulation as by striking off the surplusage under the influence and action of a reciprocating screed, that a more dense andlonger wearing pavement slag results as set forth inLetters Patent to William Ord, No. 1,532,138.

It has also been demonstrated that a smooth and uniform concrete pavement surface is best obtained by means of reciprocating surfacing devices, such as screeds, which are properly guided to ,effect striking off, compacting and smoothing said, surface, 3 l

A large number of patents have been granted covering devices and methods for subjecting plastic concrete to vibration before and after its deposit upon a pavement strip and in some in-- stances, subjecting the deposited material to vibration at the same time that it is leveled off and smoothed. l

L The main results obtained by subjecting plastic concrete to vibration are to liberate airandsure plus moisture from the mass and to cause its component solids to be brought into closer and more intimate surface contact with each other without causing relative displacements of such solids such as sinking the crushed stone to the lower part of the mass and causing sand, graveland cement mortar, to accumulate in the upper portion of the mass, or effecting a mal-distribution of such solids. ,The main object of the present invention is to provide a machine for laying plastic concrete pavements wherein the advantages of the several machines, devices and methods heretofore proposedand used are obtained by a single mechanism which subjects the plastic material to violent and substantially vibratory agitation from substantially the moment of its discharge from the mixing machine until it rests in finished condition upon the pavement strip, and at the same time, obtaining the added advantage of initial high level disposition of the mass for further promotion of its ultimate density in the finished pavementl 1 j Qther and minor objects of the invention will be pointed out in or readily understood from the following specification.

A suitable embodiment of the invention is illustrated in the accompanying drawings, wherein:

Fig. lis a top plan View of a machine constructed in accordance with the invention.

Fig. 2 is a side elevation of same partly in vertical, longitudinal section. i l

Fig.3. is a vertical, longitudinal, sectional view showing the screeds and the operating mechanism. V V

Fig. 4 is a fragmentary detail,-vertical, transverse sectional view of the machine taken on the line 4-4 of Fig. 2.-

Fig. 5 is a fragmentary detail, plan, sectional view on the line 5-5 of Fig.=2, showingconnection between the front screed of the machine and an apron plate of the discharge spout of the hopper.

'In said drawings the machine is shown as consisting of a suitable rectangular frame composed of conventional steel beams, such as channel bars and I-beams or the like, and which includes the side frame members I and 2, cross frame mem bers 3, 4, 5, 6 and I and additional connecting frame members which need not be, specifically described. v

Mounted upon said frame in the front end portion thereof is a hopper 8 having a vertical rear wall 9 and an inclined front wall In, said walls being rigid with the side walls of said hopper which covers practically machine.

The spout or delivery end portion of said hopper comprises a frontplate I I extending from the lower edge of the inclined front wall In and which ispivotally suspended, as, for example, by means of hinges I2 at the lower edge of the front wall of the hopper. The lower edge of the rear wall 9 of the hopper terminates substantially in horizontal alignment with the lower edge of the front wall I0. The said plate II is free from the side walls of the hopper and preferably is equipped with a flexibleapron I3 composed of relatively stiif rubber belting or other suitable material which projects appreciably below the lower edges of said plate I I and practically down to the crown of the fine-grade of the pavement strip disposed between the side forms I4 upon which the machine travels. The lower edgeof the plate II is disposed practically slightly above the level of the crowns of the side forms I4 and the side walls of the hopper are disposed substantially in alignment at their lower ends with the inner edges of the crowns of the side forms so that material deposited in the the entirewidth of the hopper will be delivered'over the entire width of the pavement strip between said side forms- The traction wheels l5 upon which the frame of the machine is supported by means of the customary trucks I6, are suitably driven by means of gearing connecting the same'with the engine IT. The latter is mounted between the side portions of the machine frame and is suitably geared to a shaft |8 journalled in bearings I9 which are mounted upon the lower faces of the cross frame members 20 which are secured to the lower flanges of the side frame members I and 2 and to intermediate frame members parallel therewith.

A particular description of the gearing connecting the said shaft IS with the shaft of the engine I1 is omitted as being superfluous and capable of being selected by persons skilled in the art; this being true also of the gearing connecting the traction wheels l5 with the engine shaft. The said gearing connecting the engine shaft withshaft I8 is such as to drive the latter at high speed as,for example, 1500 to 3000 R. P. M.

Disposed in front of and behind the said shaft |B are screeds 2| and 22, respectively, which span the entire width of the pavement strip and preferably overhang the crowns of the side forms l4. Each of said screeds comprises, in the main, a channel member set with its flanges extending upwardly, the front flange 23 of the front screed 2| extending to a height above the leve1-of the lower edge 'of the rear wall 9 of the hopper andbeing disposed in closeproximity to, but spaced from the latter. A flexible apron 24 of rubber or other suitable material is secured tothe lower end portion of the rear wall 9 of the hopper and extends over the entire length thereof andin cludes a depending free edgeportion 25 which is disposed in front of the screed 2| and is forced and held in contact with the flange 23 of said screed 2| by the pressure of concrete passing through the discharge spout of the hopper. 1 Each of said screeds 2| and. 22 is equipped at proper points between its ends with bearings 26 for shafts 21 with which links or connecting rods '28 are pivotally connected. 'Said linksare also pivotally connected at their upper ends with shafts 29 disposed in vertically adjustable bearlugs 30 carried by frame members and said bearings are suitably connected with adjusting screws 33 by means of which the position of the screeds 2| and 22 relatively to the level of the crowns of the side forms are suitably adjusted. I

The bearings for the shafts 21 and 29 include metal sleeves'or bushings 34 which are mounted in rubber or similar sleeves 35 snugly fitted into 7 the said bearings 30 and". 26, said rubber sleeves constituting shock absorbersof a well known type.

The shaft i8 is equipped with sets of diametrically opposed eccentrics 36 one of said sets of eccentrics being connected with the pitmen or connecting rods 31 and effecting reciprocation of the rear screed 22. The other set of said eccentrics is connected withthe pitmen, or connecting :rods 38 for effecting reciprocation of the screed 2 Said eccentricshave.athrow-radially of about -ofan inch-so as 'to impart to the'screed a reciprocatingmotion of approximately% inch, it being obvious, of course, that this may be in- .creased or diminishedwithin certain limits with- ,out departing from the invention. With reference ,to Fig. 1, it will be noted that the screeds are connected atv two points, respectively, each with'the eccentrics on the shaft l8. A larger number of points of connection. may be The latter are mounted in" guides 32 adopted, if necessary, depending upon the length of said screeds 2| and 22 and upon other engineering factors.

Mounted upon the front plate 23 of the screed 2| is a conventional angle-bar 39 forming a V- shaped rib along the entire length of the screed and the lower face of which is substantially tangential to the rounded or radiused front lower corner 39a of the screed 2|.

The screed 2| is connected in a suitable manner as, for example, by means of links or connecting rods 4| with the plate ll of the hopper so that the latter will rock in harmony with the reciprocation or rocking of the screed 2 In operation of the machine, suitable means are provided, of course, for maintaining the hopper filled with concrete, as, for example, by disposing one or more concrete mixers in advance of and for travel in advance of said machine and which deliver concrete to said hopper. Provision may also be made to cause concrete delivered into the hopper to be spread uniformly to a substantially given level within the same by mechanisms and means for feeding concrete into the hopper and spreading the same, as aforesaid being well known or readily designed by competent mechanics or engineers. V

i The high speed of the shaft l8 and consequent extremely rapid but also short stroke of reciprocation of the screeds 2| and 22 causes the concrete which is disposed in the lower end portion of thehopper to be agitated with a violent motion which serves to impart violent shocks alternately to opposite faces of said portion and effect lateral displacements thereof relatively to, but without separation from, the over and underlying portions of the mass. This causes the mass to become compact and to liberate air and surplus moisture from the same and produces a pounding and grinding action'within the agitated portion of the mass which acts to convert the mortar forming constituents of the same into plastic mortar and to effect uniform distribution of said mortar through the said agitated portion of the 1 mass. This violent agitation is caused to be directed both upwardly to the mass of material in the main body of 'the hopper and also down.- wardly upon the concrete or plastic mass which has been and is being delivered upon the pavement strip from the hopper and has the effect of promoting liberation of air and surplus moisture from the plastic material so that the deposited plastic material will fill the space between the side forms HI uniformly with a densely and uniformly compacted mass of the plastic material The apron I3 secured to the plate II and which projects practically into contact with the surface of the pavement strip, serves to preventthe plastic material delivered from the hopper from flowing forward appreciably beyond the hopper mouth and serves to maintain the density of said mass at this point by preventing portions of the mass from separating from the remainder thereof.

The agitation of the concrete or other plastic mass in the discharge spout of the hopper obviously promotes and accelerates the normal gravity discharge from the hopper and this serves also to subject this flowing portion of the mass to the pressure of the head of concrete disposed in the body of the hopper which also promotes appreciably the compacting of the deposited paving material. The agitation of the material coupled with the equivalent of hydrostatic head of the surplusagein the hopper exert so great a also to flow forward of the plate H to a far greater degree than would result from unaided flow by gravity from the hopper.

1 The very rapid short stroke motion of the screeds acts also by" surface contact with the plastic material deposited upon the pavement strip to continue thecompactio-n of the sameby forcing down into it all upwardly projecting pieces with a hammerlike effect. This causes displacement by forward motion of the laid material dis posedin advance of the screed acting upon such parts instead of moving the same along the surface and scoring the latter as occurs frequently in present day pavement finishing machines.

Preferably, the rear screed 22 is adjusted to ride substantially upon the crowns of the side forms, whereas the forward screed 2| ordinarily is raised out of contact with. the crown of the side forms M so as to permit a surplus mass of concrete to accumulate upon the pavement strip.

In practice, it is found that the rapid reciprocation and short motion of the screeds 2i and 22 causes the side forms and the screed to vibrate,

but by reason of reciprocation or very slight rocking movements of the screeds in a substantially horizontal plane, the force of vibration is distrlbuted differently from. the customary direction of impact and produces a far better effect, and does not produceimpacts on the side forms tending to displace or sing the same.

i I The level of the finished concrete disposed below and subjected to the action of the screed 2i will Slightly high, as, for example, from {g to the side forms and acts to effect further and generally final compaction to the predetermined contour and level of the pavements and which is aided by the intense vibration to which the concrete is subjecteddirectly underneath said screed In practice, after the screed 2?. has passed over the deposited plastic paving material, the latter is finished smoothly and uniformly over its entire surface to the predetermined contour of crown and the mass behind the screed 22 is compacted uniformly throughout to, a density that is substantially perfect.

It has been found .alsothat by the use of the machine of this invention, plastic concrete of a very stiff nature, as, for example, Portland cement concrete containing very little water may be used with better results than. has been possible by the means employed heretofore in attempting to utilize such relatively dry mix, as it iscalled, in the highway paving art.

Generally the plastic pavement surface is fbelted in the usual and customary manner, after the machine has passed over the same.

It has: been demonstrated in practice that the speed of travel of the machine must be in direct ratio to the speed of rotation of the shaft It for the reason that the greater the speed of the latter, the more rapidly the concrete will flow from the hopper and acquire its greatest density sothat if the machine travels too slowly in pro,

portion to the speed of rotation of the shaft Hi, the pressure of the head of concrete in the hopper with its increasingly rapid acquisition of greater density, causes the deposited concrete to surge upwardly behind the screed 2| to a higher level than that which normally is desired and further it is found that the greater the speed of rotation of the shaft I8 the better adapted the machine is for depositing of so-called dry mix concrete upon the pavement strip.

In, Fig. there is illustrated the hinged apron plate I I of the discharge spout of the hopper. The latter is reinforced over its entire length by a steel member such as the angle bar 46. The latter is equipped at its ends with trunnions or stud-shafts 32 to which links or connecting bars 4| are connected, the latter beingconnected also with the outer ends of the screed 2| in a similar manner so that the movements of said screed are transmitted to said apron plate ll.

I'claim as my invention:

1. A machine of the type set forth comprising a vehicle equipped with a hopper for plastic material and having a delivery opening extending over the entire width of a pavement strip, an apron member below and bordering said opening at the front and arranged to limit spill of material in'advance of said opening, a screed spanning the pavement strip and bordering said opening at the rear thereof and connected and co operating with said apron member to provide a discharge spout for said hopper, means for vertically adjusting said screed for determining the level of material deposited on the strip, and mechanism for impartingtosaid screed and said apron member a high speed short-stroke substantially reciprocatory movement longitudinally of the strip for subjecting discharging material to violent mass movements immediately following flow from the hopper and prior to its deposit upon said strip and at the same time compacting and surfacing said deposited material immediately following its deposit upon the strip.

2. A machine of the type set forth comprising a vehicle equipped with a hopper for plastic material and having a delivery opening extending over the entire widthof a pavement strip, an apron member belowand bordering said opening at the'front and arranged to limit spill of materialin advance of said opening, a screed spanning the pavement strip and bordering said opening at the rear thereof and cooperating with said apron member to provide a discharge spout for said hopper, means for vertically adjusting said screed for determining the level of material deposited on the strip, a projection at the front of said screed presenting oppositely inclined surfaces at top and bottomthereof, and mechanism for imparting to said screed and said apron'membar in unison a high speed short-stroke substantially reciprocatory movement longitudinally of the strip for subjecting discharging material to violent massmovements and at the same time projecting said mass alternately against said apron member and said wall'portion opposed thereto and at the same time compacting and surfacing materialdeposited upon the strip, said surfaces of said projection acting to distribute the zone of influence of said agitation to material inthe hopper and to material deposited upon the pavement strip.

3. An apparatus for converting concrete mix into plastic, workable concrete comprising means for confining the mix, and mechanism for imparting high speed motion bodily to said confining means successively in different directions through predetermined lengths of stroke, whereby to impartcorresponding mass movements to the mix and causethe same to be projected alternately against different surfaces. 7 V

A machine of the type specified'comprising a vehicle adapted for travel over a surface of deposit for plastic paving material, an open bottom receptacle for such material mounted upon said vehicle and having its open bottom disposed at an elevation above said surface of deposit, a chute disposed between said open bottom of said receptacle and said surface of deposit and having an open bottom disposed at an elevation spaced from said surface, saidchute, positioned relatively to the open bottom of said receptacle to cause all material discharged from the latter to pass through said chute progressively during travel of the vehicle, and power actuated mechanism on the vehicle connected with said chute for effecting high-speed movements of the latter in successively different directions in a plane substantially parallel with the plane of travel of the vehicle, thereby to impart mass movements to material flowing through said chute progressively relatively to material disposed above and below the same and prior to deposit of said material progressively along said surface during travel of the vehicle.

5. A machine of the type specified comprising a vehicle, a substantially reciprocable member car-' ried thereby and disposed above and spaced from a surface for deposit of concrete mix, said member presenting a passage for concrete mix therethrough, a receptacle for said mix disposed to deliver same progressively into one end of said passage for flow progressively therethrough preparatory to its discharge upon said surface, and mechanism for imparting substantially reciprocatory movement to said member at high speed for subjecting mix in passage through the same to mass projection alternately against opposed walls of said member.

6. A machine of the type specified comprising a vehicle, an open bottomed receptacle mounted thereon, a chute disposed immediately below'the open bottom of the receptacle for causing all material discharged from the latter to pass therethrough and be confined between opposed walls of said chute, mechanism for imparting rapid forward and back movements in unison to op-' posed walls of said chute through a predeter- 'mined appreciable length of stroke whereby to thereon and adapted to receive concrete mix to be deposited progressively upon a road bed'along which is adapted to travel, a chute disposed immediately below the open bottom of the hopper for causing all material discharged from the latter to pass therethrough and be confined therein preceding its dischargeupon the roadbed, the said chute being spaced from said roadbed a distance substantially equal to the predetermined depth of the pavement composed of said mix, said chute including a pair of opposed walls connected witheach other and both movable relatively to the hopper in the, general direction of travel of the vehicle, mechanism on the latter connected with said walls for imparting to them in unison rapid to-and-fro movements in the last-mentioned general direction relatively to said hopper for imparting to mix confined between said walls a mass movement relatively to mix disposed within the hopper and at the same time projecting said mass alternately against said receptacle walls for condensing and compacting said means immediately preceding its depositupon the roadbed.

' 8. A machine of the type specified comprising a carriage equipped with an open bottom receptacle including a discharge spout equipped with a pair of opposed walls movable relatively to the body of the receptacle and through which the material is adapted to flow by gravity, a strike-off and finishing screed disposed to constitute one of said walls of said spout, and mechanism connected with said screed and the other walls of said spout for moving thev latter and reciprocating said screed rapidly in a direction substantially parallel with the travel of the carriage thereby to impart to material disposed within the discharge spout mass movements laterally of its downward flow and during the latter through said spout.

9. A machine of the type specified equipped with a receptacle for plastic material having an open bottom disposed at an elevation above and spaced from the predetermined profile of a finished pavement slab to be deposited upon an area over which said machine is adapted to travel, a chute arranged relatively to the receptacle bottom to cause all material discharged from the latter to pass therethrough and which occupies the space between said receptacle bottom and the said pavement profile, and mechanism on said machine for imparting to said chute rapid, substantially reciprocatory movements relatively to the receptacle in successively opposite directions substantially horizontally for imparting mass movements and shocks to the material disposed within said chute relatively to material in the receptacle and relatively to material previously deposited during travel of machine.

10. A machine of the type specified comprising a vehicle, an open bottom receptacle rigidly mounted thereon and having its said bottom disposed at a selected elevation above the surface of deposit of plastic concrete passing through said receptacle, the discharge end portion of said receptacle being movable substantially bodily relatively to the body of said receptacle in a direction laterally of the flow of material through said receptacle, mechanism for imparting to said movable portion of the latter a sharp and rapid forward and back movement of appreciable length of stroke continuously during travel of the vehicle, and means associated with said-mechanism for controlling the speed of travel of the vehicle and thereby controlling the rate of flow from said receptacle upon the surface of deposit and the consequent period of subjection of flowing material to the action of said movable discharge portion of said receptacle,

11. A machine of the type specified comprising a vehicle, an open bottom receptacle rigidly mounted thereon, means for affecting travel of the same along and parallel with a surface of deposit spaced from the bottom of said receptacle, an open chute carried by the vehicle and disposed below and in substantial alignment with the opening in the bottom of the receptacle for causing all material flowing from the latter to pass through said chute, means supporting the chute and maintaining the lower end thereof spaced from the surface of deposit, and mech anism for effecting high speed substantially reciprocatory movements to said chute relatively to said receptacle continuously during travel of the latter, thereby to effect projection of the mass disposed within the chute alternately against opposed walls of the latter preceding its discharge from said chute, and flexible means spanning the space between said chute and the bottom of the receptacle for guiding the mix into said chute.

12. In a machine of the type specified, a member open at top and bottom and disposed for passage of concrete mix therethrough progres sively during travel of the machine preparatory to deposit of said mix upon a surface over which said machine travels; a receptacle for mix disposed to deliver the same into said member by gravity, and mechanism for imparting to opposed walls of said member in unison highspeed substantially reciprocatory movements for subjecting mix during passage between said walls to mass projection alternately against said respective walls. i

13. In a machine of the type specified, a member open at top and bottom and presenting opposed walls for passage of concrete mix therebetween progressively during travel of the machine preparatory to deposit of said mix upon a surface over which said machine travels, a receptacle for mix disposed to deliver the same between said opposed walls of said member by gravity, and mechanism for imparting to said Walls in unison high-speed substantially reciprocatory movements in a direction laterally of the direction of flow of mix therethrough and longitudinally of the travel of the machine and relatively to said receptacle, and a pavement surfacing screed rigid with and projecting rear- Wardly from the rear wall of said member.

14. In a machine for treating concrete mix immediately preceding deposit of same in place for setting, a receptacle for said mix, substantially reciprocable spaced apart opposed walls disposed below said receptacle for receiving mix therebetween as the same is discharged from said receptacle and during flow thereof toward the place of its ultimate deposit, mechanism for imparting to said opposed walls in unison a substantially reciprocable movement relatively to said receptacle at high speed for imparting to the mix while disposed within the zone of influence of said walls mass movements in alternately opposite directions against said respective walls and laterally of the general direction of its flow from the receptacle to the place of deposit, and relatively to mix disposed within the receptacle and previously deposited mix, and a surfacing and finishing screed connected with and operating in unison with said opposed walls.

15. A machine of the kind specified including a vehicle, an open bottom receptacle for concrete mix mounted thereon, a substantially reciprocable chute, open at top and bottom, disposed below and substantially in register with the opening of the receptacle bottom, flexible aprons bordering the bottom of the receptacle and secured along their upper edges to the latter and depending at their lower, end portions into said chute for guiding mix from said receptacle into said chute during actuation of the latter, and mechanism for imparting substantially reciprocato-ry movements to said chute at a speed sufiicient to effect intensive projection of the mass of the mix within said chute alternately against opposed walls of the latter, and at the same time moving said chute and its contents relatively to the receptacle and the material within the same.

ALFRED W. FRENCH. 

